Journal of Human Kinetics volume 18 2007, 73‐86 73 © Editorial Committee of Journal of Human Kinetics Physical Endurance and Swimming Technique in 400 Metre Front Crawl Race by Marek Strzała1, Aleksander Tyka2, Piotr Krężałek3 The aim of the observation was to examine the relationships between en- durance indices and technique parameters on 400 m front crawl swim- ming. 26 swimmers were examined (16.1±1.09 years. Basic body variables (BH 177.5±8.07 [cm], BM 65.4±9.40 [kg]) and maximal oxygen uptake during arm crancking or leg cycling (3.14±0.54 and 3.82±0.53 [l.min‐1] respectively) were measured. The examination was conducted during 400 metre swimming (average speed 1.42±0.07 [ m.s‐1]) beginning from wa‐ ter at a 50 m pool. Stroke rate (SR), stroke length (SL), propulsion (PL, PS) and non‐propulsion phases (E, R) as well as index of coordination (IdC) for arms were measured. Leg movement quantity (LQ), was counted from the same shots as arms. There was a significant dependence of 400 m swimming speed on PL+PS level, IdC and SR (r=0.69, 0.50, 0.50 re- spectively) characterizing athletes technique. Front crawl swimming technique parameters were analyzed during four successive 100m seg- ments of the 400 m distance. In spite of reduced stroke length, the in- creased stroke rate enabled swimmers to maintain speed in successive 100 metre segments or even accelerate, (especially in the last 100 m). The relation between SL and LQ was statistically significant r=0.41, p=0.04 and influenced stroke length. The correlation between SR and LQ was negative, close to statistical significance r= -0.36, p=0.07. Moreover, correlations between AR, WLLTAR, TWAR and V400 were insignificant and reached an average level (r=0.28-0.36). Key words: swimming, stroke parameters, oxygen uptake, anaerobic threshold 1 - Department of Theory of Water Sports, Academy of Physical Education in Cracov, Poland 2 - Department of Physiology, Academy of Physical Education in Cracov, Poland 3 - Department of Biomechanics, Academy of Physical Education in Cracov, Poland 74 Physical endurance and swimming technique in 400 meter front crawl race Introduction 400 m freestyle swimming using front crawl technique has been performed for over a hundred years. The first race at the distance of 440 yards took place at the Olympic Games in St. Louis. Leading specialists in front crawl swimming at shorter (Pieter van der Hoogenband and Ian Thorpe) and long distances (Grant Hackett and Yuri Prilukov) compete additionally at middle distance race. Com‐ plex examination of the prominent competitors enables sport scientists to de‐ termine the most important factors limiting performance at 400m. Empirical studies in the field of sport swimming are focused mainly on research analyzing the effects of applying different swimming techniques in short and long dis‐ tance races on the swimmers’ speed, as well as the role of aerobic and anaerobic endurance indices. Some authors point out the essential role of the anaerobic component (Sharp et al. 1982, Keskinen et al. 1989), while others suggest, that aerobic efficiency, is the most important factor (Obert et al. 1992, Wakayoshi et al. 1995). Others stress the importance of such factors as swimmers morphologi‐ cal and structural properties (Avlonitou et al. 1997, Grimston et al. 1986, Seifert et al. 2007). They play an important role in the hydrodynamic formation of swimming technique, and they are focused on during front crawl training (Ber‐ ger et al. 1999, Touissaint et al. 1992, 2004, 2005, Kolmogorov et al. 1992, 1997). The aim of this observation was to examine the relationships between physi‐ cal endurance indices and technique parameters in 400 m front crawl swim‐ ming. Materials and methods 26 swimmers aged from 15 to 18 years were examined. They signed a writ‐ ten informed consent. The research project received an approval of the Bioethics Commission in Cracow (No 292/KBL/OIL/2004 from 17th November 2004). On the basis of the data collected during anthropometric measurements, the following variables were estimated: somatotype (using the method introduced by Carter‐Heath 1990), percentage of body fat (PF) and lean body mass (LBM) (using the Slaughter et al. 1988 formula). Total body length (BTL) was measured while the subjects were lying on their back with their upper extremities ex‐ tended above the head, and ankles plantar‐flexed. Arm span of abducted arms was measured between the right and left arm from the fingertips. The measur‐ ments were performed using appropriate anthropometric instruments (Sieber Hegner Maschinen AG, Switzerland) and Harpenden‐type foldmeter of con‐ stant pressure (10 g cm‐2). by M. Strzała et al. 75 Upper limb tests (and TWAR) were conducted in a sitting position on an ergometer adapted for arm cranking (843E‐Ergomedic, Monark, Sweden). Lower limb tests were conducted on a cycloergometer ER 900 Jaeger (Germany) and TWLG on a cycloergometer 874E‐Ergomedic (Monark, Sweden). During the anaerobic 60s TWLG test the ergometer breaking resistance was set at 7.5% of BM, and during the 60s TWAR – 4.5% of BM (Bar‐Or 1987, Lutosławska 1995). The graded exercise test evaluating was preceded by a three minute warm‐up (WU) at intensity of approximately 45% of , after which every three minutes the resistance was increased by 30W. The intensity of the exercise during WU at was 150W or 120W depending on the swimmers’ age and endurance level. The tests were preceded by WU at the intensity of 90 or 60W also depending on the age and endurance level, and every 3 minutes the resistance was gradually in‐ creased by 18 and 12W respectively. Graded exercise was continued until voli‐ tional exhaustion at a pace of 70 rpm at LG and 60rpm at AR. Breathing ex‐ change variables were measured using a 919ER Medikro (Finnland) apparatus. In the last 30 seconds of each segment load in AR and LG a capillary blood samples were taken to determine lactate concentration (La) using a Mini‐ fotometer Plus Dr Lange (Germany). The research procedure adopted by the authors enabled them to determine simultaneously, both the anaerobic thresh‐ old (AT) using Dmax technique (Cheng et al. 1992) and maximal oxygen uptake (AR and LG). The field tests were conducted during 400 m swimming beginning from water at a 50 m pool. The parameters used for assessing swimming technique were measured at the end of each 100 m segment of the distance (between 75 and 90m, excluding the 5 metre zone before the turn). Duration of the race and the intermediate time of covering particular distances were measured using a stop watch with a precision of 0.01s. Swimmers’ movements were recorded with a rapid shutter speed GRV 9800 JVC (Japan) video camera at a frequency of 50 shots per second. The recordings were executed from a side view about 1 m below the water surface. Two complete upper limb cycles were analyzed. Since the arm movements in the front crawl are cyclic, the cycles were sepa‐ rated and divided into phases in the recorded movement. The identification of the intracyclic phases was conducted according to the Chollet method (2000) (Fig. 1) Cycles were divided into phases according to characteristic events during hand and arm movement. Each phase was specified according to its role in ac‐ celerating the swimmer’s body (propulsion or non‐propulsion phase). The first is the entry phase (E – Entry, non‐propulsion) – from the entry of the hand into the water till the beginning of its backward movement. Then there comes the 76 Physical endurance and swimming technique in 400 meter front crawl race first propulsion phase (PL – Pull) – from the end of the entry phase till the mo‐ ment when the arm is vertically raised above the humeral joint. Then, the sec‐ ond propulsion phase (PS – Push) – from the vertical position of the arm till the arm release from the water. The cycle ends with the non‐propulsion phase (R – Recovery) – from the hand’s release from the water to its next entry into the water. E R PL PS Fig. 1 Front crawl upper extremity intracyclic phases division scheme The following parameters were used to assess swimming technique during each analyzed 20m long swim (i=1,2,3,4): ‐ swimming speed: Vi=20m / Δti ‐ stroke rate (SRi), calculated as the reciprocal of the arithmetical average of duration of two analyzed swimming cycles: SRi=1/Ti ‐ stroke length (SLi), calculated as the average speed to SRi ratio: SLi=Vi/SRi The swimming cycles of both arms are typically phase‐shifted. Depending on the chosen extremities coordination method, such a shift results in the occur‐ rence of periods without any propulsion (when none of the extremities is in the propulsion phase) or periods with double propulsion (when both extremities are in the propulsion phase). To assess the upper extremities cooperation in body propulsion a parameter called index of coordination (IdCi) is used. It is expressed as percentage of cycle duration: t k1 − t k 2 R PL IdCi = ∗100% Ti k1 where: tR – beginning of R phase for the first arm, k 2 tPL – beginning of PL phase for the second arm, Ti – duration of swimming cycle, by M. Strzała et al. 77 IdC has a positive value when propulsion phases interfere, but when there is a pause between them it takes negative value. Legs movement quantity (LQi), counted from the same shots as arms movements, were qualified as six‐beat kick, corresponding to six complete al‐ ternating immersion and/or emersion movements in one upper extremities movement cycle, and four‐ and two‐beat kick, for four and two leg movements in one arm movement cycle respectively.